1. Field of the Invention
The present invention relates to a card-shaped radio communication module which is installed to electrical apparatuses such as a personal computer, a wireless telephone, and an audio apparatus, and adds radio communication function there to, and an antenna device which is comfortably used in the card-shaped radio communication module.
2. Description of the Related Art
Recently, along with digitization of data, information such as music, speech, images and other various data can be obtained easily from a personal computer or mobile computer. Furthermore, such information is band-compressed by undergoing the speech codec technique or image codec technique, and is delivered to a variety of radio communication terminal equipment easily and efficiently by digital radio communication or digital radio broadcasting. For example, audio video data (AV data) can also be received by a wireless telephone.
On the other hand, systems for transmitting/receiving data are being utilized in household as well as various environments by the use of simplified radio communication network systems which can be employed even in a region of a small scale. As the radio communication network systems, radio communication systems for next generation such as the 5 GHz narrow-band radio communication system proposed in IEEE 802.1a, 2.45 GHz band radio LAN system proposed in IEEE 802.1b, and a short-range radio communication system termed Bluetooth are worthy of notice.
There has been proposed a personal computer system in which a card-sized radio LAN card 50 adds radio communication function to a personal computer 2 or a main apparatus 2. The main apparatus 2 can transmit/receive data among apparatuses constituting the system when the radio LAN card 50 is installed to a slot 3 thereof, as shown in FIG. 1. The radio LAN card 50 has a module main body 51 and an antenna unit 52 provided at one side thereof. The radio LAN card 50 has a radio communication controlling unit and a high frequency signal processing unit built therein. The radio LAN card 50 is electrically connected to the main apparatus 2 when the module main body 51 is installed to the slot 3 thereof. At this time, the antenna unit 52 is exposed to the outside to transmit/receive data among the apparatuses, as shown in FIG. 2.
In the radio LAN system proposed in IEEE 802.1b, a radio LAN card conforming to the PCMCIA (Personal Computer Memory Card International Association) is widely utilized. On the other hand, in the Bluetooth radio communication network system, a small-sized radio LAN card having radio communication function has been developed.
When the radio LAN card 50 conforming to the PCMCIA is installed to the slot 3 of the main apparatus 2, the antenna unit 52 protrudes from the side of the main apparatus 2 by a length 1 being approximately 25 mm, as shown in FIG. 2. Furthermore, an external antenna, not shown, is mounted to the antenna unit 52 so as not to be prevented from transmitting/receiving data among the apparatuses by the main apparatus 2, which undesirably makes the main apparatus 2 complicated and enlarged.
In case the main apparatus 2 is a portable apparatus such as a note type personal computer or mobile apparatus, the protruding length of the radio LAN card 50 is too large and cumbersome. So, the radio LAN card 50 is often broken when hit by the user by mistake. Furthermore, even though the radio LAN card 50 can add radio communication function to various apparatuses, the configuration shape is restricted, which undesirably raise the difficulty in designing with high degree of freedom.
There are proposed antenna apparatuses of variety of configurations, and an inversed F type antenna is used as a built-in antenna of a relatively simplified configuration. The inversed F type antenna has an antenna pattern, a short circuit forming pattern, and a feeding pattern. The short circuit forming pattern has an end thereof connected to an end of the antenna pattern perpendicular thereto, and the feeding pattern has an end thereof connected to the halfway portion of the antenna pattern in parallel with the short circuit forming pattern. Thus, the inversed F type antenna of an inversed F shape is configured. The direction of the main polarized wave of the inversed F type antenna crosses perpendicular to the antenna pattern thereof.
FIG. 3 shown a schematic view of an antenna device 60 in which a pair of inversed F type antenna patterns being a first inversed F type antenna pattern 62 and a second inversed F type antenna pattern 63 are formed perpendicular to each other. The direction of the main polarized wave of the first inversed F type antenna pattern 62 is a1 and that of the second inversed F type antenna pattern 63 is b1, thereby configuring polarization diversity. Thus configured antenna-device 60 requires a height h, which makes it difficult to reduce the size thereof. So, in case the antenna device 60 is used as the antenna unit 52, the radio LAN card 50 is undesirably enlarged.
The radio communication function is added to various apparatuses such as a digital still camera, a video camera or a portable audio apparatus as an AV apparatus, a household electrical apparatus, and an entertainment robot, as well as a radio communication apparatus and an apparatus in a computer system. Especially, with a portable apparatus, forming a plurality of communication ports or installing hardware conforming to various standards induce enlargement and high price of the apparatus, which significantly prevents the diffusion thereof. Furthermore, the radio communication function is significantly affected by interference generated at the same frequency band or at different frequency bands.
Since the radio LAN card is used in above-described various apparatuses as well as a radio communication apparatus and an apparatus in a computer system, a small-sized antenna device which does not protrude so much from a main apparatus and has polarization diversity characteristics is required extremely.
It is therefore an object of the present invention to overcome the above-mentioned drawbacks by providing a small-sized antenna device which has polarization diversity characteristics.
It is another object of the present invention to provide a radio communication card module which has a small-sized antenna unit whose protruding length from a main apparatus is made minimum when installed and adding radio communication function thereto and has polarization diversity characteristics.
According to the present invention, there is provided an antenna device which has at least a first antenna pattern being an inversed F type antenna pattern and a second antenna pattern being a meander type antenna pattern formed on the main surface of a dielectric substrate by printed wiring. The inversed F type antenna pattern and the meander type antenna pattern are wired so that the directions of the main polarized wave of these antenna patterns cross perpendicular to each other. There is formed a short circuit forming pattern on the dielectric substrate between the inversed F type antenna pattern and the meander type antenna pattern. There is formed a ground pattern on the dielectric substrate in the vicinity of a feeding portion of the meander type antenna pattern. The meander type antenna pattern has a point in the vicinity of the opened end thereof connected to a circuit unit formed on the dielectric substrate or to a short circuit forming pattern formed on the dielectric substrate between the inversed F type antenna pattern and the meander type antenna pattern.
With the antenna device according to the present invention, having the inversed F type antenna pattern and the meander type antenna pattern whose directions of the main polarized wave cross perpendicular to each other, the antenna device can be reduced in size and configure polarization diversity, and whose antenna characteristics is not deteriorated when affected by the housing shape of a main apparatus or material thereof when installed to the main apparatus, which can realize transmission/reception of data or information with high accuracy. Furthermore, with the antenna device, the short circuit forming pattern can prevent the inversed F type antenna pattern and the meander type antenna pattern from affecting each other. Furthermore, with the antenna device, by forming a ground pattern and a circuit unit in the vicinity of the meander type antenna pattern, shunt capacitance is add to reduce the resonance frequency, while realizing impedance matching of the meander type antenna pattern.
According to the present invention, there is also provided a radio communication card module which has a module main body having a radio communication controlling unit and a high frequency signal processing unit built therein, an antenna unit, and a connector unit. The antenna unit is mounted to a second side located on the opposite side of a first side which has the connector unit, and a dielectric substrate which has at least a first antenna pattern being an inversed F type antenna pattern and a second antenna pattern being a meander type antenna pattern formed on the main surface of the dielectric substrate by printed wiring is supported perpendicular to the insertion direction toward a main apparatus.
The radio communication card module is installed to a slot of the main apparatus and the connector unit is connected to a connector unit of the main apparatus, and adds radio communication function to the main apparatus. When the module main body is inserted to the main apparatus and supported therein, the antenna unit protrudes from the side of the main apparatus by a length being the thickness thereof along the side direction of the main apparatus. With the radio communication card module according to the present invention, the protruding length of the antenna unit from the main apparatus can be made minimum. Furthermore, with the radio communication card module, having the inversed F type antenna pattern and the meander type antenna pattern whose directions of the main polarized wave cross perpendicular to each other, the radio communication card module can be reduced in size and configure polarization diversity, and whose antenna characteristics is not deteriorated when affected by the housing shape of a main apparatus or material thereof when installed to the main apparatus, which can realize transmission/reception of data or information with high accuracy.
These objects and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention when taken in conjunction with the accompanying drawings.